I've noticed that many of the post in the "Help!" section of this forum are related to fermentation issues. Most of these come from self described "beginner" brewers so I thought I'd post a few "best practices" here:

1. Pitch plenty of healthy yeast. If your beer has a gravity above 1.044, make a starter. The higher the gravity the bigger the starter. If you're brewing a barley wine near 1.100, a 1 gallon (4 litre) starter is appropriate. Remember, you aren't pitching all of that liquid into your wort, just the slurry and enough liquid to get the slurry out of the container. For lager brewing, I always create a 1 gallon starter.

2. Aerate/oxygenate your wort. If all you have available is shaking the carboy/bucket do that. It is better than nothing. The yeast needs oxygen. If you are using pure O2, be careful to not over oxygenate. There are plenty of places you can look research this.

3. Use nutrients. They are relatively inexpensive and will help your fermentation. If you're making a starter, use the nutrients in the starter.

4. Pay attention to the recommended temperature range for your yeast strain. It is printed on the package for a reason. If you stray from this range and you have problems, well, duh! Yes, it is possible to be successful outside the recommended range, but there is a lot to learn about fermentation so you'd better have a pretty good handle on a lot of those variables if you're going to disobey the recommendations of the yeast experts.

5. Take gravity readings. It goes without saying that you need to sanitize your equipment and be careful to not contaminate when doing this, but knowing the progress of your fermentation can help you nurture the beer along when you get close to your terminal gravity, go ahead and start boosting the temperature a little to help finish it off. The flavor profile is already there, you aren't going to hurt it if you're just trying to get the job finished for the last few points.

6. Patience. Yes, fermentations can complete in just 3 days but that is under ideal/optimum circumstances. Even when my fermentations do complete that quickly, I still let the beer sit on the yeast for the remainder of the week before I rack to secondary or bottle/keg. This time allows the yeast to clean up any byproducts produced by fermentation. You aren't running a commercial brewery where you need to empty your tanks for the next batch of beer in order to stay profitable. Remember that a lager is going to take a lot longer to ferment than an ale if you're fermenting at the proper temperatures.

Following these procedures will get you a properly fermented beer. A good fermentation will turn a mediocre recipe into a good beer. A poor fermentation will turn the best recipe into a bottle of swill.

One other tip I'd like to throw your way. While many beer styles require the proper yeast strain to recreate, it isn't always necessary to use the same yeast a particular brewery uses to create their style of beer. There are so many other fators at play that will produce a beer that tastes different than their beer that the exact yeast strain they use is the least of your issues. If you brew a lot of English style ales, then find an English ale yeast that works well for you and use it. The same is true for American ales. Understanding how a couple of yeast strains ferment will provide predictability to your beers. If you change something else in your process and you don't get the profile you expected from your trusted yeast, you can have more confidence that the process is the cause not the yeast. If you change the process and the yeast then you have no idea which caused the difference.